2011/11/22 by Shailesh Chandrasekharan, Chandrasekharan, Shailesh, Anyi Li +1
Mathematics · Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Phenomenology (hep-ph) #Markov Chains and Monte Carlo Methods #Nuclear Theory (nucl-th) #Quantum Chromodynamics and Particle Interactions #Stochastic processes and statistical mechanics #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.str-el #hep-lat #hep-ph #nucl-th
paper · pdf · doi:10.48550/arxiv.1111.5276
14 pages, 5 figures, 1 table, contribution to Lattice 2011, July 10-16, 2011, Squaw Valley, Lake Tahoe, California, USA
arxiv created 2011/11/22 · openalex publication_date 2011/11/22 · arxiv updated 2011/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a new approach to some four-fermion lattice field theories which we call the generalized fermion bag approach. The basic idea is to identify unpaired fermionic degrees of freedom that cause sign problems and collect them in a bag. Paired fermions usually act like bosons and do not lead to sign problems. A resummation of all unpaired fermion degrees of freedom inside the bag is sufficient to solve the fermion sign problem in a variety of interesting cases. Using a concept of duality we then argue that the size of the fermion bags is small both at strong and weak couplings. This allows us to construct efficient algorithms in both these limits. Using the fermion bag approach, we study the quantum phase transition of the 3D massless lattice Thirrring model which is of interest in the context of Graphene. Using our method we are able to solve the model on lattices as large as 403 with moderate computational resources. We obtain the precise location of the quantum critical point and the values of the critical exponents through this study.